The present invention relates generally to electrical lighting devices, and, more particularly, to an electrical lighting device utilizing light emitting diodes (LEDs).
A light-emitting diode (LED) is a semiconductor diode based light source. When a diode is forward biased (switched on), electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence, and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. When used as a light source, the LED presents many advantages over incandescent light sources. These advantages include lower energy consumption, longer lifetime, improved robustness, smaller size, faster switching, and greater durability and reliability.
However, the LED as a light source has its disadvantages. One of the disadvantages is that the light emitted from a LED chip concentrates in a direction normal or perpendicular to the surface of the LED chip. That is, LED light is strong in the upright direction and drastically diminished in the sideway directions. In order to make a LED light more like a traditional incandescent light source with uniform light emitting intensity in all directions, reflectors have been used to redirect the LED beam from upright to sideways. However, redirecting light merely sacrifices light in the upright direction in favor of sideway directions and may not be an efficient uniform wide-angle light source.
As such, what is desired is a LED light bulb that can uniformly emit light in most directions from the LED chip.